Thermal switch



June 7, 1949. G. c. ARMSTRONG THERIIAL S'ITCH Original Filed April 3.1945 INVENTOR Georg-e C/?rmafraoyr ATI'ORNEY WITNESSES: 647

'space within the central bore of body l contains Devices according tothe invention may be used Patented June -7, 1949 i I UNITED- STATESPATENT OFFICE 2,472,0s2' THERMAL SWITCH George C. Armstrong, Pittsburgh, Pa., asslgnor to Westinghouse Electric Corporation, EastPittsburgh, Pa., a corporation of Pennsylvania Original applicationApril 3, 1945, Serial. No. 586,287. Divided and this application August15, 1946, Serial No. c9o,63

7 Claims. (Cl. 200-122) This invention relates to thermally operatedsion of the tube 2 without loosening it from the electric contacts orrelays, for instance, for overadjoining metal parts. v load protection,and is submitted as a division The modification shown in Fig. 2 has ametal from my copending application 'Serial No. body ll which isprovided with a terminal [2 and the mercury is displaced and changes itslevel ductive connection between the contact !4 and when suflicient heatis applied to volatilize the the contact nger !3. The annuar space aboveliquid; and the change in'level is used for causing the mercury I 1 andaround the'finger l3 contains the mercury to make or break an electrccona quantty !8 of volatile liquid. Heating of the nection between,contacts associated with the un to a mpe a u e above the bOlng pointstructure. of the liquid causes sudden evaporaton of liquid It is anobject of my invention to provide |8 and hence increases the pressureabove the devices of the just-mentioned type which are mercurysuifciently to force it out of contact is equipped with 'an electric orexpansible conunits of Figs. 1 and 2.' .According o tainer whichencloses a quantity of mercury as tubular metal part IS is connectedwith a second well as a quantity of volatile liquid, and this contubularmetal -part by an insulating seal or tainer is associated with contactsurfaces which insert 2! consisting, for instance, of gia-ss or areinterconnected and disconnected by the other vitreous mater'al. Abellows 22 is flrmly These and other features ot the inventio w electriccontact between the parts s and 20, and beunderstood from 'the followingdescription oi' hence between the circuit leads 24 and 25 solthose'embodiments shown in Figs. 1, 2 and 3 dered or otherwise fastenedthereto. A quantity respectively of the drawing. v of volatile liquid,denoted by 26, is disposed in .i In the embodiment shown in Figure 1 abody 5 the remaining space within the tubular part !9, l of metal is'connected by an elastic tube 2 with and a heating coil 21 is providedfor causin t e minals 5 and 6, respectively, for connection to sure thendeveloped within' part s forces the the circuit'to be controlled by therelay unit. A 40 mercury23 downwardly under expansion of the quantity ofmercury denoted by 1 is provided in bellows 22. As a result, theelectric connection the interier of the structure, and the remainingbetween parts -l9 and 20 is interrupted.

an amount of volatile liquid denoted by 8. When* fo overload protectionof electric circuits and for of contact with the body l. The tubularportion Relay-s according to the invention and as de- 2 consists of asufiiciently elastic material, for scribed in the foregoing can bemanufactured' instance, natural or synthetic rubber or a polywithextremely small overall dimenslons as compolyvinyl chloride. Theconnection of the elastic current Capacity. advantage, in conjunc.- tube2 with the body l and the contact 3 is sumtion with the small compass orthe device, is parciently resistant and tight to permit anexpanticularly important for using the relays as a coma vaosa inventionas set forth in the claims annexed hereto.

I claim as my invention:

1. An electric contact device, comprising a.

heatable and expansible container structure of variable' Volume having aquantity of, mercury enclosed by said structure, a quantity of volatileliquid disposed in said structure so as to volatilize when suflicientlyheated in order to then expand the Volume of said structure, saidcontainer structure having two interior contact surfaces insulated fromeach other and engageable by said mercury quantity" so as to beelectrically interconnected and disconnected by said mercury quantitydepending upon the change in mercury level caused by the change inVolume of said structure. i V

2. An electric contact device, comprising a heatabie and expansibiecontainer structureof variable Volume consisting at least partly ofmetal and having two interior contact surfaces insulated from eachother, and a quantity of mercury encosed by said structure, a quantityof volatile liquid disposed in said structure so as to volatilize whensuificiently heated in order to then expand the Volume of saidstructure, an eiectric heating coil disposed on said metal part of saidstructure for heating said liquid, said surfaces being electricallyinterconnected by said mercury quantity in a given Volume condition ofsaid structure 3. An electric contact device, comprising avariable-volume container structure having two rigid metallic endportions and an intermediate portion of insulating elastic material, aquantity of mercury disposed in said structure so as to normally contactsaid two end portions, and a quantity of volatile liquid disposed insaid structure so as to volatilize when sufliciently heated in order ,tothen expand said intermediate portion whereby said mercury quantitychanges its level and' electrically disconnects said end portions.

4. An electric contact device, comprising a variable-volume containerstructure having an expansible bellows and being provided with twointerier contact surfaces insulated from each other, a quantity ofmercury enclosed by said structure, a quantity of volatile liquiddisposed in said structure so as to volatilize when sumciently heated inorderto then increase the Volume of said structure by expanding saidbellows. seid surfaces being 'arranged relative to said mercury quantityso as to be electricaly interconnected and disconnected bythemercurydepending upon the change m mercury level caused by the change in Volumeof said' structure.

5. An electric contact device, comprising a;

variable-volume container structure,having a tubular and substantiallyrigid portion and an expansible and metallic bellows portion and 'aninsulating annular portion disposed between said i tubular portion andsaid .bellows portion, a quantity of mercury disposed in said structurefor I establishing electric' contact between said tubular portion andsaid bellows portion, and a quantity of volatile liquid disposed in saidstructure so as e to volatilize when sufliciently heated' m order tothen expand said be11ows;'-portion whereby 'said mercury quantitychanges its level and electrically disconnects said end portions.

6. 'An eiectric contact device, comprising a.

`variable-volime container structure having a.

tubuiar and substantially rigid portion and an expansible and metallicbellows portion and an insulating annular portion of vitreous materialforming a seal between said tubular portion and said bellows portion, aquantity of mercury disposed in said structure for establishing electriecontact between said tubuiar portion and said bellows portion, and aquantity of volatile liquid disposed in said structure so as tovolatilize when- J suiciently heated in order to then expand saidbellows portion whereby said mercury quantity changes its level andelectrically disconnects said end portions.

7. An electric contact device, coniprising a variable-volume containerstructure having a tubular and substantially rigid portion and anexpansible and metallic bellows portion and an insulating annularportion disposefbetween said tubular portion and said bellows portion, aquantity of mercury disposed in said structure for establishing electriccontact between said tubular portion and said bellows portion, and aquantity of volatiie iiquid disposed in said structure so as 7 tovolatilize when sufliciently heatedin order to then' expand said bellowsportion whereby said mercury quantity changes its level and electricallydisconnects said end portions. and an ele'ctric heating coi disposed onsaid tubular portion for heating said liquid.

` GEORGE QARMSTRONG.

. REFERENES CITED The following references are of record the file ofthis patent:

UNITED STATES PATENTS

